Carlo Ancelotti was left fuming after Chelsea were denied what appeared a blatant penalty in the first leg of their Champions League quarter final against Manchester United at Stamford Bridge.
The Blues lost 1-0, but the Chelsea players claimed they should have had a spot-kick in injury time when Ramires appeared to be brought down by United full-back Patrice Evra.
Spanish referee Alberto Mallenco waved away the appeals to allow United to take a narrow advantage to Old Trafford, courtesy of a Wayne Rooney first-half strike, in the second leg next Tuesday.
Ancelotti said of the penalty claim: "It was clear. For everyone. Everyone knows it was clear.
"The problem is I know it's sometimes not easy to give the penalty in the last minute and you need to have personality, courage and character. Not always do referees have these kind of skills.
"I'm disappointed but this is the result. Not just the referee, but the assistant was in the right position to decide that was a penalty. I said to the referee (after the game) that it was a penalty and he needed to whistle. He said nothing. No answer.
"The players are aggrieved. But we have to forget it and be focused for the next game. We have to try our best there."
Ancelotti believed his side had been unlucky and admitted they now had an uphill task.
He said: "It's not easy, but I think we have to try. Obviously we know it will be difficult to win there. We have confidence to do it. Last year it was the same - we had to win at Old Trafford and we did this.
"We are at a disadvantage now, but the performance was good. Not 100% but, in general, we had good control but conceded a goal too easily. We had opportunities, worked hard, and had a clear chance to have a penalty at the end.
"We hit the post in the first half. We had some opportunities to score: we didn't deserve to lose, but it doesn't matter. We have to change the result at Old Trafford. It's just 90 minutes. We have another 90 minutes to play.
"If we were 1-0 up it would be a different situation at Old Trafford. Now we're 1-0 down and we have to play attacking football to win this game."
Chelsea keeper Petr Cech could not believe that the Blues were not awarded a spot-kick for Evra's crude lunge on Brazilian Ramires.
"I think everybody saw what happened, you can see clearly on the TV," he said. "But the most important person did not see it.
"We lost the game and we have left ourselves a mountain to climb but we have to do it.
"I think we created chances and that was the key. They had their first chance and scored and we had some but we didn't score, and that's the difference."